Nematode communities as indicators of status and processes of a soil ecosystem influenced by agricultural management practices

Nematode communities were monitored for three years in a citrus soil ecosys tem in Central Florida under various agricultural regimes comparing standar d vs, reduced-input practices. Differences in agricultural regimes consiste d of two fertilization levels, two irrigation levels, and two types of grou nd cover under the tree (herbicide vs. mulch). While some nematodes were af fected sporadically by fertilization and irrigation treatments, mulch had a consistent and frequently significant effect on many bacterivores, fungivo res, herbivores, and omnivores. Rhabitidae, Cephalobus, Aphelenchus, and Ap helenchoides had an immediate but temporary response to mulch additions. Ac robeles, Acrobeloides, Eucephalobus, Teratocephalus, Criconemoides, Aporcel aimellus, and Eudorylaimus were always less abundant in mulch-treated plots , whereas Plectus and Belonolaimus were always more abundant. Of various in dices of community composition, only maturity indices, unlike diversity ind ices, indicated the status and intensity of soil processes (decomposition, mineralization). However, different responses of single genera within a tro phic group implied unique contributions of nematode genera in soil ecosyste m processes on a temporal scale, suggesting that generic or possibly specie s level of resolution provide the most adequate information about the soil ecosystem. (C) 1999 Elsevier Science B.V. All rights reserved.